The cold gas spraying method referred to above is known for example from DE 102 24 780 A1, wherein particles that are intended to form a coating on a substrate requiring to be coated are injected into a cold gas jet generated by means of a cold spray nozzle and accelerated by means of the latter preferably to supersonic speed. Consequently the particles strike the substrate with a high kinetic energy which is sufficient to ensure adhesion of the particles on the substrate or to one another. In this way coatings can be created at high deposition rates, with a thermal activation of the particles not being necessary or being necessary only to a limited extent. Thermally relatively sensitive particles can therefore be used for forming the layer. Due to the requirement to inject a kinetic energy into the particles it is necessary for these to exhibit sufficient mass inertia. The cold gas spraying is therefore limited to particle sizes in excess of 5 μm.
If it is desired to produce nanostructured layers by using nanoparticles, then according to U.S. Pat. No. 6,447,848 B1 a thermal coating method can be used. In this case the nanoparticles are suspended in a liquid and fed with said liquid to the flame jet of the thermal coating method. Mixtures of liquids can also be used in this process, thereby enabling the composition of the nanostructured layer to be influenced. The use of thermal spraying is limited to applications of this method on layer materials having a high temperature stability if the nanostructuring of the supplied nanoparticles is to remain intact (e.g. ceramic particles).